Human hemoglobin of G-Makassar variant has been reported very rarely with Beta Thalassemia. In year 1969 Hb G- Makassar was first identified in Makassar, Sulawesi (Celebes), Republic of Indonesia. The disease was first published in 1969 and 33 years later it has been reported at a fam- ily of Thailand origin. We report a 45-year- old Malay man who was investigated for anemia and thrombocytopenia then diag- nosed with Hb G-Makassar. This finding describes as a new Hemoglobin G- Makassar discovered in Malaysia after 14 years diagnosed in Thailand.

Introduction

Hemoglobin (Hb) G-Makassar muta- tion was first identified in Indonesia, which are bound Malaysia and the Southeast Asia. Blackwell et al. were described the patient was living and origin of Thailand. 1The Hb G-Makassar electrophoretic mobility slow- er-moving β hemoglobin variant exhibited to have its anatomical abnormality at the β- 6 or A3 location where the glutamyl residue typically is replaced by an alanyl residue. 2,3Meanwhile the substitution of single amino acid in the gene encoding β-globin subunit β-6 glutamyl to valine will result as sickle cell disease. 4Both routine hemoglobin elec- trophoresis separation by cation-exchange High Performance Liquid Chromatography (HPLC) and cellulose acetate electrophore- sis were unable to separate Hb G-Makassar and Hb S where they were found to share the same identical properties. As a result, Hb G-Makassar and Hb S could be incor- rectly identified for each other and therefore can be misdiagnosed as Sickle Cell Disease (SCD). 5

Case Report

A 45-year-old man was previously investigated at Malaysian private hospital for anemia and thrombocytopenia for a year. His platelet was normalized while ane- mia remained. He then presented to Malaysian government hospital of Haematology Centre with symptomatic anemia and bleeding haemorrhoids. He had frequent bleeding haemorrhoids in the past that required intermittent blood transfusions management. He has no hepatplenomegaly. Counts on presentation at our centre was; Hb: 5.7 g/dL, MCV: 68.9 fL MCH:

(Ferum) was 2.4 μmol/L and ferritin was 5.5 μg/L before started iron therapy. Both iron and ferritin level were improved after iron therapy. The latest ferritin level was 53.4 μg/L in 2017. Peripheral blood film showed tha- lassemia pictures but did not reveal any sickle cells. Hb analysis was initially sug- gestive of compound heterozygous state of Hb S/E. However, β DNA analysis revealed compound Heterozygous codon 26 [GAG>AAG] HbE (β E) and codon 6 (GAG−>GCG) Hb G-Makassar mutations while α DNA analysis showed negative result of mutations. Apart of haemorrhoids, the patient is otherwise asymptomatic. After he had surgery for haemorrhoids, his Hb was stable ranging from 9 g/dL to 12 g/dL, MCH 19 pg to 25 pg, MCV 63 fL to 74 fL.

He was transfusion independent and only treated with iron therapies. He also does not need regular follow up. During follow up, he never has jaundice. His total bilirubin was 8 μmol/L and did not raised. The retic- ulocyte percentage was normal but the absolute reticulocyte count was low with 0.67% and 0.029 x10 6/μL respectively.

Results

Figure 1 reveals that the morphology of red blood cell on peripheral blood smear of this patient was microcytic hypochromic anemia with presence of occasional target cells (stain was purchased from Sysmex Malaysia Sdn. Bhd.). This finding could be related to heterozygous β variant (Hb E) detected in this patient as in Hb G- Makassar, it was reported as normal mor- phology. The typical feature of sickle cell anemia such as boat-shaped cell or sickle cell was not seen. Figure 2 demonstrates that Hb Makassar variant moved to the same loca- tion as Hb S, which was detected at zone

Acknowledgments: the authors would to thanks to all Haematology Clinical Referral Laboratory staff for their technical assistance. We extend our special thanks to all staff of Molecular Genetics Laboratory, Haematology Unit, Institute of Medical Research, Kuala Lumpur Hospital for their help to complete this report.

Received for publication: 4 May 2018. Revision received: 11 July 2018. Accepted for publication: 31 July 2018.

This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License (CC BY-NC 4.0).

while minimal Hb A and Hb F was identi- fied. Hb A2 was minimally elevated. This can be mistakenly identified as Compound Heterozygus state of Hb S/E thalassemia. Figure 3 demonstrates that the mobility of the hemoglobin variant Hb G-Makassar in cellulose acetate electrophoresis was identical to Hb S. Therefore, the effect of alkaline pH was not accomplished to sepa- rating Hb S, Hb Punjab and Hb Tak through cellulose acetate hemoglobin electrophore- sis. Hence, they appear to migrate to the same position as the Hb F. Hb G-Makassar also retained at the same location as Hb S at acidic pH on cellulose acetate hemoglobin electrophoresis. Because of this similarity, the differential diagnosis of the variants are periodically problematic. 6-8

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Figure 4 describes a DNA sequence on β DNA analysis using PCR amplification that confirmed Hb G-Makassar mutation (GAG -> GCG). DNA molecular analysis of the β-globin genes identified the GAG -> GCG mutation in codon 6 where the muta- tion bound for Hb G-Makassar [β6(A3) Glu -> Ala]. In addition, he also had a single point mutation in the codon 26 causing β E- thalassemia, [GAG -> AAG]; he is aggre- gate heterozygote for Hb G-Makassar/ β E- thalassemia. The Hb G-Makassar mutation was first diagnosed using Polymerase Chain Reaction-Restriction Fragment Length Polymorphism (PCR-RFLP) technique. It was detected by Acil restriction site in the 886 bp fragment, and this fragment was fur- ther absorbed on 645 and 241 bp fragments, correspondingly in the Hb G-Makassar allele, variant of the second nucleotide of the codon 6, A -> C.

Hemoglobinopathies are inherited abnormalities of globin chain synthesis and Sickle cell anemia is the commonest mono- genic diseases as described by Thom et al. 9Piel and David recently reported more than 1000 natural mutation in the human hemo- globin variants. These hemoglobin variants were found to be the effect of single amino acid substitutions throughout the gene mol- ecule. The clinical effects of the hemoglo- bin variants are vary ranging from clinically insignificant to severe forms of hemoglobin disorder. 10Nevertheless, over 300,000 babies are estimated to be delivered every year with one of these abnormalities. 11Sickle-cell disease is most commonly found in sub-Saharan Africa, and parts of the Mediterranean region, the Middle East and the Indian subcontinent. Meanwhile Beta- thalassemia is most common among popu- lations of Mediterranean, African and South Asian ancestry. The prevalence for Southeast Asia is 0-11% of population. However, the incidence of Hb G-Makassar remains less informative as reported by Weatherall and Piel. 12-14Many variants of the β- and α-globin chain will migrate like Hb S under the con- ditions of alkaline electrophoresis though some variants such Hb D or Hb G can be separated by acid electrophoresis but not Hb G-Makassar. Hb G-Makassar cannot be distinguished from Hb S by isoelectric focusing, HPLC, globin chain electrophore- sis or hemoglobin electrophoresis. 15Table 1 shows the identification of Hb G-Makassar in this case was obtained by β DNA sequence analysis, which revealed a single nucleotide substitution GAG−>GCG of β-

(β E). As there was no sickle cell noted on peripheral blood film, sickling test can be performed to identify the presence of Hb

S.16,17

Hemoglobin electrophoresis of this patient showed predominantly Hb G- Makassar (63.0%), presence of Hb E (25.7%), minimal Hb A (4.6%) and Hb F (2.1%). After reviewed his DNA analysis, he was diagnosed as compound heterozy- gote Hb G-Makassar/βE-thalassemia. The clinical expression of this was a β-tha- lassemia minor phenotype. In correlation to his clinical features, he has no splenomegaly and no signs of hemolysis. Hence, the presence of Hb G-Makassar was appeared to be functionally proportionate to Hb A. The level of Hb A2 in Hb G-

Makassar trait (ranging from 3.7% to 4.7%) and compound heterozygosity with β O-tha- lasemia (9.1%) were noted to be higher than typically present in normal controls (rang- ing from 2.3% to 3.2%) and β O-thalassemia

traits (ranging from 4.0% to 6.0%). This is similar to Hb S trait and Hb S/β-tha- lassemia. Increased of Hb A2 might reflect of an elevation of α-globin chains available for tetramer formation with δ-globin chains, indicating a minimally reduced affinity of the βS with the α chain. An analogous explanation may employ to Hb G-Makassar variant. Position of the structural change of Hb G-Makassar occurs at the same as in Hb S, however their clinical manifestations are absolutely different. Homozygous expres- sion of Hb S concludes sickle cell disease, which is a vaso-occlusive condition and

chronic hemolytic anemia that can some- times be fatal. 15Hb G-Makassar heterozy- gotes are haematologically normal and clin- ically asymptomatic but Hb G- Makassar/β 0-thalassemia compound het- erozygote has attribute to thalassemia minor. On the other hand, homozygous Hb G-Makassar is almost normal and did not have any abnormal clinical feature. Nevertheless, the Hb G-Makassar was viewed and become less informative on their clinical phenotype and haematological disorder. The difference in clinical manifes- tations of these two hemoglobin variants might be due to the alteration of the Glu −> Ala side chain which is not produced enough for polymerization and generation of red cell sickling.

There are high possibilities of Hb S and Hb G-Makassar presences in ethnic group such multiracial groups as a result of popu- lation migration. As Hb G-Makassar cannot be differentiated from Hb S on both acid and alkaline electrophoresis, DNA analysis would be the definitive for the diagnosis of Hb G-Makassar.